1. Field of the Invention
The present invention is related to surgical pumps, and particularly to peristaltic pumps for use in ophthalmic surgery.
2. Description of Related Art
It is well known to use pumps in surgery, including ophthalmic surgery, to pump aspirant (fluids and tissue) from a surgical site, such as a patient's eye. Such pumps vary in the method used to pump aspirant including venturi pumps, scroll pumps, and peristaltic pumps.
Peristaltic pumps are well known in ophthalmic surgery and typically include a rotating pump head with a plurality of rollers spaced about the circumference of the pump head. These rollers typically cooperate with a backing plate to pinch closed a small section of tubing placed between the rollers and backing plate. As the pump head rotates, the rollers revolve and provide a continuous pinch point along a length of tubing. The rollers and backing plate are constructed that multiple rollers will pinch closed the tubing. In this way, as the pump head rotates, a flow of liquid and tissue is created within the tubing. In this way, a length of aspirant tubing is connected to one end of the pump tubing and a collection reservoir, typically a bag is connected to the other end of the pump tubing. Thus, aspirant is peristaltically pumped from a surgical site to the collection bag.
Peristaltic pumps typically, require that a length of tubing be placed and held between the pump head and a backing plate. Getting the tubing between the pump head and backing plate has typically been achieved in one of three ways. The first method is to manually thread the tubing between the head and plate. This is somewhat cumbersome, time consuming, and inconvenient for a user. The second and third methods include the use of a cartridge that has a length of tubing exposed. The second method includes a threading member or finger that extends beyond the pump head and, as the pump head rotates, the finger threads the tubing onto the pump head. This requires a specially designed threading finger but generally results in an easy to load pump. A third method includes a cartridge with a portion of the cartridge forming the backing plate. The cartridge is then urged toward the pump head. This method is also convenient for the user but has a potential drawback in that the backing plate of the cartridge typically does not cooperate with the pump head over a sufficiently large radius. This relatively small radius of interaction can lead to unwanted pulsation in aspirant flow through the system.
One other prior art peristaltic pump does not use any backing plate at all. Instead, a cartridge with a loop of tubing is place around a pump head and a cartridge holder is then moved away from the pump head until the tubing loop is sufficiently stretched that the rollers of the pump head pinch closed the tubing without a backing plate. The extent to which the tubing must be stretched is a cause for concern. Also, without a backing plate unwanted pulsation is likely to occur. This pulsation can result in dangerous and undesirable intra-ocular pressure in the eye and may also effect chamber stability during surgery.
Therefore, it would be desirable to provide a peristaltic pump with the convenience of a cartridge that is easily loaded by a user.